132 The Philippine Journal of Science 1923 



Since some kinds of eels are oily and more indigestible than 

 many other fishes, this belief is evidently founded on sound 

 observations but faulty deductions. The convalescent dies of 

 indigestion after a hearty meal of eel, not from a recurrence 

 of the disease. 



Eels are among the greediest and most active of fishes, though 

 like many other fresh-water fishes they are much more active 

 by night than by day. They not only devour anything living 

 that is small enough for them to catch, but also delight to feed 

 upon any kind of dead or even putrid carcass. 



From time immemorial students have puzzled over the time 

 and place where eels spawned. Every spring vast hordes of 

 tiny young eels ascended the rivers, making their way over 

 waterfalls, dams, and even crawling through damp grass to 

 places not to be reached by swimming. Here, far from the sea, 

 they reached a large size but no sexual development followed. 

 In the fall large eels were observed going downstream, these 

 being the ones caught in the eel pots that the fishermen set in 

 the estuaries. All sorts of theories and speculations were ad- 

 vanced to account for the mystery, and it was not until 1707 

 that the female eel was first made known, while the male was 

 not discovered until 1873. Many more years of patient inves- 

 tigation were required before the life history of the European 

 and American eels was known, while that of the Indo-Pacific 

 eels is still almost a total blank. 



When the European eels attain proper maturity they make 

 their way downstream to salt water. Continuing westward 

 they ultimately reach the edge of the continental shelf and 

 drop off into the depths, still westward bound. On arriving 

 in salt water their gonads develop rapidly, and by the time 

 they reach the western Atlantic they are ready to reproduce. 

 In a region about 27° north and 60° west, southwest of Ber- 

 muda, and at a depth of about 500 fathoms, the eggs are laid 

 and fertilized, the adults then perishing. Our knowledge of the 

 location of the spawning grounds is due to the investigations 

 of Dr. Johannes Schmidt, of Copenhagen. The American eel 

 has its spawning places in a zone west and south of the European, 

 but overlapping. The larvae of both species appear to pass 

 their earliest stages together, but when they are about 3 centi- 

 meters long one species turns toward Europe, the other toward 

 North America. 



